U.S. patent application number 14/051251 was filed with the patent office on 2015-04-16 for dynamic lumbar support for a chair.
The applicant listed for this patent is James E. Grove. Invention is credited to James E. Grove.
Application Number | 20150102647 14/051251 |
Document ID | / |
Family ID | 52809083 |
Filed Date | 2015-04-16 |
United States Patent
Application |
20150102647 |
Kind Code |
A1 |
Grove; James E. |
April 16, 2015 |
DYNAMIC LUMBAR SUPPORT FOR A CHAIR
Abstract
A dynamic lumbar support located within the back of an office or
home chair to enable a user to be seated close to a work surface
(e.g., a desk or a table). The chair back rocks back and forth when
the user shins his weight backwards and forwards. The dynamic
lumbar support includes a cushion back support manufactured from a
resilient material that is responsive to a compressive force
applied thereto when the user reclines and shifts his weight
against the chair back. In particular, the cushion back support is
adapted to change its shape from a relaxed convex shape at which to
support the user's lower back and maintain a proper posture when
the user sits erect and the chair back stands upright to a
compressed flattened shape at which to support the users back when
the reclines and the chair back bits backwards.
Inventors: |
Grove; James E.; (Marina del
Rey, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Grove; James E. |
Marina del Rey |
CA |
US |
|
|
Family ID: |
52809083 |
Appl. No.: |
14/051251 |
Filed: |
October 10, 2013 |
Current U.S.
Class: |
297/284.4 |
Current CPC
Class: |
A47C 7/46 20130101 |
Class at
Publication: |
297/284.4 |
International
Class: |
A47C 7/46 20060101
A47C007/46 |
Claims
1. A claim, comprising: a seat to support the weight of a user; a
back to support the back or the user arm adapted to tilt, forwards
and backwards; and a dynamic lumbar support located within said
chair back and including a cushion back support having a first
protruding shape that engages and supports the users lower back
when the user sits erect in the chair and the chair back tilts
forwards, said cushion back support changing to a second flattened
shape when the user reclines in the chair arid leans back so that
the chair back tilts backwards.
2. The chair recited in claim 1, wherein the cushion, back support
of seal dynamic lumbar support has a convex configuration at the
first protruding shape thereof so as to fit within the hover back
of the user when the user sits erect in the chair and the chair
back bits forward, said cushion back support being compressed to
said second battened shape when the user reclines in the chair and
the chair back tilts backwards.
3. The chair recited in claim 1, wherein the cushion back support
of said dynamic lumbar support is manufactured irons a resilient
material that is responsive to a compressive force applied thereto,
said cushion back support having said first protruding shape when
the user sits erect in the chair and the chair back tilts forward,
and said cushion back support changing to said second flattened
shape when the user leans back and applies a compressive force
against the chair back to correspondingly cause the chair back to
tilt backward, and the cushion back support to be compressed.
4. The chair recited in claim 3, wherein said dynamic lumbar
support also includes a back pressure-responsive rod which extends
horizontally through said chair back, said back pressure-responsive
rod moving up and down through said chair back depending upon
whether the user is sitting erect and said cushion back support has
said first protruding shape or the user leans back and said cushion
back support has said second flattened shape.
5. The chair recited in claim 4, wherein said dynamic lumbar
support also includes at least one track extending vertically in
said chair back, said horizontally-extending back
pressure-responsive rod riding up and down along said track
depending upon whether said cushion back support has said first
protruding shape or said second flattened shape.
6. The chair recited in claim 5, wherein said dynamic lumbar
support also includes a flexible sheet having a spring memory and
covering said cushion back support to push said back support having
said first protruding shape into engagement with the user's lower
back, said flexible sheet being stressed and storing energy in
response to the compressive force applied to the chair back, to
cause said cushion back support to change from said first
protruding shape to said second battened shape, and said flexible
sheet relaxing and releasing its stored energy to cause said
cushion bank support to change from said second flattened shape to
said first protruding shape when the compressive force applied to
said chair back terminates.
7. The chair recited in claim 6, wherein said back
pressure-responsive rod is attached to said flexible sheep whereby
said rod is coupled to sand cushion back support covered by said
flexible sheet.
8. The chair recited in claim 6, wherein said dynamic lumbar
support also includes a sheet bending rod which extends
horizontally through said chair back so as to lie against said
flexible sheet and thereby urge said sheet towards a curved
configuration for correspondingly pushing said cushion back support
into engagement with the users lower back.
9. The chair recited in claim 6, wherein the chair back includes a
rigid backing located therewithin and covered by upholstery, said
one track along which said back pressure-responsive rod rides up
and down being connected to said rigid backing.
10. The chair recited in claim 9, wherein said rigid backing has an
opening formed thereat, said flexible sheet being located alongside
said opening so that said cushion back support is received through
said opening.
11. The chair recited in claim 5, wherein said dynamic lumbar
support also includes a tension strap spaced Com said cushion back
support, said tension strap having one end thereof connected to
said back pressure-responsive rod and an opposite end connected to
a hinge at winch said tension strap is rotated backwards and
forwards when the chair back tilts backwards and forwards and said
back pressure-responsive rod rides up and down along said
track.
12. The chair recited in claim 11, wherein said tension strap is
pivotally coupled to said hinge.
13. The chair recited in claim 11, further comprising a base to
hold the chair seat above the around, a gas cylinder receiver
located below: the chair seat, and a gas cylinder located between
the base and the gas cylinder receiver to adjust the height of the
chair seat, wherein said dynamic lumbar support also includes a
tilt plate located below the chair seat and having one end thereof
coupled to said tension strap at said hinge and an opposite end
coupled to the gas cylinder receiver.
14. The chair recited in claim 13, wherein said tension strap
rotates backwards and forwards at said hinge relative to said bit
plate at the same time that the chair back tilts backwards and
forwards and said back pressure-responsive sod rides up and down
along said track.
15. A chair, comprising; a seat to support the weight of a user; a
back to support the back of the uses and adapted to tilt forwards
and backwards; and a dynamic lumbar support located within said
chair back and including a cushion back support having a first
shape that engages and supports the user's lower back when the user
sits erect in the chair and the chair back tilts forwards, said
cushion back support adapted to change to a second shape when the
user reclines in the chair and leans back so that the chair back
tilts backwards, a back pressure-responsive rod extending
horizontally through said chair back, and a tension strap coupled
to said back pressure-responsive rod and rotating in opposite
directions when the chair back tilts backwards and forwards to
correspondingly cause said back pressure-responsive rod to move up
and down through the chair back.
16. The chair recited in claim 15, wherein the first shape of the
cushion back support ok said dynamic lumbar support is convex so as
to protrude towards and fit within the lower back of the user when
the user sits erect in the chair and the chair back tilts forward,
the cushion back support being compressed and flattened to the
second shape thereof when the user reclines in the chair and the
chair back tilts backwards.
17. The chair recited in claim 16, wherein the cushion back support
of said dynamic lumbar support is manufactured from a resilient
material that is responsive to a compressive force applied thereto,
said cushion back support having said first convex shape when the
user sits erect in the chair and the chair back tilts forward and
said cushion back support being flattened to have said second shape
when the riser leans back and applies a compressive force against
the chair back to correspondingly cause the chair back, to tilt
backward and the cushion back support to be compressed.
18. The chair recited in claim 17, wherein said dynamic lumbar
support also includes at least one track extending vertically in
said chair back, said horizontally-extending back
pressure-responsive rod moving up and down through said chair back
and along said vertically-extending track depending upon the
direction in which the tension strap of said dynamic lumbar support
is relating.
19. The chair recited in claim 18, wherein said dynamic lumbar
support also includes a flexible sheet having a spring memory and
covering said cushion back support to push said back support having
said first convex shape into engagement with the user's lower back,
said flexible sheet being stressed and storing energy la response
to the compressive force applied to the chair back to cause said
cushion back support to be flattened from said first convex shape
to said second shape, and said flexible sheet relaxing and
releasing its stored energy to cause said cushion back support to
change front said second shape to said first convex shape when the
compressive force applied to said chair back terminates.
20. The chair recited in claim 18, wherein said tension strap is
coupled at one end thereof to said back pressure-responsive rod and
at the opposite end thereof to a hinge located outside and below
the chair back, said tension strap rotating in said opposite
directions at said hinge, whereby to cause said back
pressure-responsive rod to correspondingly move tip and down
through said chair back and along said vertically-extending track.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates m a dynamic lumbar support located
inside the back of a chair of the kind which rocks back and forth,
such as that, for example, commonly found In an office or home so
that a user can be sealed close to a work surface (e.g., a desk or
a table). The lumbar support is adapted to change its shape in
response to a pressure applied to the chair back so as to provide
support and maintain a proper posture of the users back at all
times when the chair back stands upright and the user's back is
erect and close to the work surface and when the chair back rocks
backwards and The user reclines away horn the work surface.
[0003] 2. Background Art
[0004] A wide variety of chairs have been used in an office or at
home to enable a user to be seated adjacent a work surface. In this
case, the user can access a computer, a book, a writing pad, etc,
winch lays upon site work surface so that the user can work while
seated. Some chairs are adapted to rock back and forth in response
to the user shifting his weight backwards and forwards. With the
chair rocked forwards, the user's back is located close to the work
surface during which work can be accomplished. When the chair rocks
backwards, the user's back, is correspondingly reclined and tilted
away from the work surface to enable the user to relax.
[0005] A common problem with such conventional office and home
chairs occurs when the chair rocks forward and the user tries to
hold his back erect and close to the work surface. In particular,
even when the back of the chair stands upright, the back of the
user is usually spaced forwardly from the chair back. Therefore,
the chair back offers no support for the user's lower back
throughout those times when the user is working. Consequently, the
user's back posture may suffer and, especially during long periods
of work, the user may experience lower back pain and
discomfort.
[0006] What would therefore be desirable is a chair which overcomes
this problem so that the user's back will be adequately supported
by the chair back so that a proper posture is maintained when the
chair rocks forward and the user's back is erect.
SUMMARY OF THE INVENTION
[0007] In general terms, a dynamic lumbar support is disclosed to
be located inside the back of a chair that has particular
application for use in an office or a home so that a user can be
seated adjacent a work surface (e.g., a desk or a table). the chair
is of the kind that rocks back and forth when the user shifts his
weight backwards and forwards. The dynamic lumbar support herein
disclosed is responsive to a pressure applied by the user against
the chair back. That is. the lumbar support is adapted to change
its shape as the user shifts his weight in the chair. By virtue of
the foregoing, the user's lower back will be supported and a proper
posture maintained when the chair rocks forward and the back of the
chair stands upright so that the users back will remain erect and
close to the work surface.
[0008] The dynamic lumbar support includes a resilient (e.g., foam)
cushion back, support that is located inside the back of the chair.
A flexible (e.g., plastic) force-receiving sheet, having a spring
memory and a normally-curved (i.e., arced) configuration is bonded
to the rear of the cushion back support. A rotatable sheet bending
rod runs across the bottom of the force-receiving sheet to apply
pressure and hold the sheet in its initially curved configuration.
The bottom of the flexible force-receiving sheet is coupled to a
cushion retention plate which lies below the seat, of the chair.
The top of the force-receiving sheet is coupled to a back
pressure-responsive rod which runs horizontally through the chair
back. Opposite ends of the back pressure-responsive rod are
received in respective ones of a pair of vertical guide tracks hurt
are affixed to a plywood backing inside the chair back. A tension
strap runs vertically through the chair back behind the cushion
back support. The top of the tension snap is attached to use back
pressure-responsive rod, and the bottom of the tension strap is
pivotally connected at a spring-loaded hinge to one end us a tilt
plate. The opposite end of the tilt plate is coupled to the
existing gas cylinder receiver which projects downwardly from the
seat plate.
[0009] When the chair back stands upwardly from the chair seat and
the user sits erect so as to be close to the work surface, the
cushion back support of the dynamic lumbar support is at rest. in
this case, the back support has a convex shape which protrudes
forwardly from the chair back to support the users lower back and
maintain a proper posture. At the same time, the back
pressure-responsive rod lies at the bottom of the pair of vertical
guide tracks. When the chair rocks back and the user reclines away
front the work surface, a compressive force is generated by the
user's back against the chair back. In this case, the convex
cushion back support is compressed and flattened by the users back,
and the flexible, normally-curved force-receiving sheet which
covers the rear of the back support is straightened so as to store
energy. At the same time, the pivotal tension strap rotates
rearwardly at tire hinge, whereby to cause the back
pressure-responsive rod that is attached to the top of the tension
strap to ride upwardly along the pair of guide tracks and
vertically through the chair back. When the compressive force being
applied to the chair back is terminated, the tension strap rotates
forward, and the straightened force-receiving sheet recovers to its
normally-curved configuration and releases its stored energy to
simultaneously cause the back pressure-responsive rod to move in an
opposite downward direction through the guide tracks and the
previously compressed cushion back support, to expand back to its
initial at rest convex shape.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a side view of a chair having a dynamic lumbar
support according to a preferred embodiment located inside the
chair back and including a cushion back support having an initial
sorest convex shape when a user leans forward and sits erect in the
chair adjacent a work
[0011] FIG. 2 is a side view of the chair of FIG. 1 with the
cushion back support of the dynamic lumbar support being compressed
and tautened when the user leans back in the chair and reclines
away from die work surface;
[0012] FIG. 3 is an enlarged detail of the cushion back support and
a flexible force-receiving sheet to which the back support is
bonded taken from the top of the dynamic lumbar support shown in
FIG. 1;
[0013] FIG. 4 is a rear view of the chair of FIG. 2 showing the
dynamic lumbar support located inside the chair back and covered by
decorative upholstery;
[0014] FIG. 5 is an enlarged detail of me cushion back support and
the flexible force-receiving sheet taken from the bottom of the
dynamic lumbar support shown in FIG. 1; and
[0015] FIG. 6 is a side view of the chair shown in FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0016] Referring concurrently to FIGS. 1-6 of the drawings, a
dynamic lumbar support 1 is shown end disclosed for use with a
chair 3. The chair 3 is preferably one that rocks back and forth
and is of the kind that would commonly be found in an office or at
home to provide a seat for one working at a desk, a table or a
similar work surface. However, the specific use of the chair 3 is
not to be regarded as a limitation of this invention.
[0017] Like a typical chair, the chair 3 shown in FIGS. 1-6
includes a seat 5 to support the weight of a user. The chair seat 5
is held above the ground by a base 6 having a set of outstretched
legs 7 to winch respective rollers 9 are attached to permit the
chair 3 to be moved from place-to-place. A gas cylinder 10 extends
between the base 6 and a gas cylinder receiver 12 that projects
downwardly from a seat plate 14. A lever arm (not shown) cooperates
with the gas cylinder 10 to enable the elevation of the seat 5 to
be adjusted to suit the needs of the user. A tension adjustment
knob 16 is accessible below the seat plate 14. The tension
adjustment knob 16 is rotated to adjust the spring tension of the
seat 5 depending upon the size and weight of the user.
[0018] The dynamic lumbar support 1 is located within the back 20
of the chair 3. As will soon be explained, the shape of the lumbar
support 1 changes in response to pressure being applied
thereagainst by the back of the user as the user shifts his weight
forwards and back. As an important advantage of this invention, and
unlike a typical borne or office chair, the lumbar support 1 is
adapted to engage and support the user's back so as to maintain a
proper posture and enhance comfort when the chair 3 rocks forward
and the chair back stands upright to enable the user to sit erect
and close to the work surface (best shown in FIG. 1). The lumbar
support 1 will also comfortably support the user's back at times
when the chair rocks back and the user reclines so that, the back
20 of the chair tilts away from the work surface (best shown in
FIG. 2).
[0019] The back 20 of the chair 3 within which the dynamic lumbar
support 1 is located stands upwardly horn the seat 5 (best shown m
FIG. 6). A bead rest 22 projects upwardly from the back 20 in axial
alignment therewith. The back 20 provides support for the user's
back, while the head rest 22 supports the user's head and neck.
Each of the back 20 and head rest 22 includes a solid (e.g.,
plywood) backing 24 and 26 winch is surrounded by filler material
and a conventional upholstered cover 2d and 29, such as that
manufactured from vinyl, leather or the like (best shown in FIG.
4). An opening 30 (also best shown in FIG. 4) is formed in the
backing 24 of the chair back 20 to accommodate the dynamic lumbar
support 1 therethrough.
[0020] The chair 3 is shown having a pair of arms 32 and 34 located
at opposite sides of the seat 5. for the chair 3 of FIGS. 1-6, the
arms 32 and 34 are bolted to and extend forwardly from the back 20.
However, the anus 32 and 34 may also be connected to the seat 5 or
to each of the back 20 and the seat S. An arm rest 36 is attached
atop each of the pair of arms 32 and 34 upon which the arms of the
user may be laid.
[0021] Details of the dynamic lumbar support 1 are now described
according to a preferred embodiment of this invention. The lumbar
support 1 includes a cushion back support 40 which is positioned
inside the chair back 20 so as to engage the lower back of a user
who is seated in the chair 3. The cushion back support 40 is
manufactured from a resilient material (e.g., foam) that is adapted
to be compressed and undergo a change in its shape in response to a
compressive force applied thereto. The rear of the cushion, back
support 40 is covered by a force-receiving sheet 42 that, is
manufactured from a flexible (e.g., plastic) material which has a
characteristic spring memory. The flexible sheet 42 is adhesively
bonded to the cushion back support 40. The flexible sheet 42 is
normally curved with, an arced configuration so as to urge the
cushion back support 40 into engagement with the user's lower back.
The sheet 42 is located at the rear of the plywood backing 24
adjacent the opening 30 formed therein, so that the cushion back
support 40 projects ahead of sheet 42 and through opening 30 to the
front of backing 24.
[0022] The cushion back support 40 of the lumbar support 1 is
coupled at the bottom thereof to a flat cushion retention plate 46
that is affixed to the bottom, of the chair seat 5 above the seat
plate 14. A linking arm 48 extends between the bottom of the
cushion back support 40 and the cushion retention plate 46. The top
of the arced flexible sheet 42 to which the cushion back support 40
is bonded is coupled to a back pressure-responsive rod 50 that
extends horizontally inside the back 20 of the chair 3.
[0023] In particular, and referring specifically to FIGS. 3 and 4
of the drawings, opposite ends of the back pressure-responsive rod
50 are received by a pair of generally j-shaped brackets 52. The
horizontally-excluding back pressure-responsive rod 50 is secured
behind the flexible force-receiving sheet 42 winch covers the rear
of back support 40 by means of a pair of fasteners 54 which extend
through the force-receiving sheet 42 and respective ones of the
pair of brackets 52,
[0024] The horizontally extending back pressure-response rod 50
which is supported by the brackets 52 lies within a pair of
generally vertical guide tracks 56. As is best shown in FIG. 4, the
pair of guide tracks 56 are affixed to the plywood backing 24
inside the back 20 of the chair 3 so as to be held in spaced
parallel alignment with one another. That is, one end of the rod 50
is slidably received within a first of the pair of guide tracks 56
at one side of hacking 24, and the opposite end of rod 50 is
slidably received in the second guide track 56 at the opposite side
of backing 24. As will soon be explained, the horizontally
extending back pressure-responsive rod 50 is adapted to slide up
and down along the vertically extending guide tracks 56 in response
to the user shifting his weight in the chair 3 and causing the
chair back 20 to either stand upright or tilt back.
[0025] As is best shown in FIGS. 4 and 5 of the drawings, the
bottom of the flexible force-receiving sheet 42 is coupled to a
sheet bending rod 66 that, like the back pressure-responsive rod
50, extends horizontally inside the back 20 of the chair 3.
However, while the back pressure-responsive rod 50 runs across the
top of the force-receiving sheet 42, the sheet bending rod 66 runs
across the bottom of sheet 42. bach of the opposite ends of the
sheet bending rod 66 is received by a respective pair of
cylindrical, hinges 67-1, 67-2 and 68-1, 68-2. In particular, a
first hinge 67-1 and 68-1 from each pair of hinges is affixed to
the plywood backing 24 of the chair back 20. A second hinge 67-2
and 68-2 from each pair of hinges is affixed to the flexible
force-receiving sheet 42. All of the hinges 67-1, 67-2, 68-1 and
68-2 are axially aligned with one another so that the sheet bending
rod 66 is rotatable therewithin
[0026] The dynamic lumbar support 1 also includes a rigid (e.g.,
steel) tension strap 58 that is spaced behind the cushion back
support 40 and runs vertically down the back 20 of the chair 3.
FIG. 4 shows one end of the tension strap 58 attached to
approximately the midpoint of the back pressure-responsive rod 50.
The opposite end of the tension strap 58 is coupled to one end of a
stationary (e.g.. steel) tilt plate 60 at a pivot such as, for
example, a spring-loaded hinge 62. As best shown in FIG. 6, the
tension strap 58 extends downwardly through and outwardly from the
bottom of the back 20 of the chair 3 so as to be pivotally
connected to the lunge 62 below the chair back. The tilt plate 60
lies below the seat plate 14, such that the opposite end of tilt
plate 60 is attached to the previously-described gas cylinder
receiver 12 of the chair 3 which projects downwardly from seat
plate 14. By way of example, the tilt plate 60 has a coupling ring
64 which is located in surrounding engagement with the gas cylinder
receiver 12 during the manufacture or assembly of the chair 3.
[0027] The operation of the dynamic lumbar support 1 within the
back 20 of the chair 3 is now explained for providing support to
the user's lower back and maintaining a proper posture whether the
chair back stands upright and the user is sitting erect while
working or the chair back bits backwards and the user reclines.
FIG. 1 shows the chair 3 rocked forward, the chair back 20 standing
upwardly from the seat 5, and the user sitting erect so as to be
close to the work surface. In this case, the resilient cushion back
support 40 of the lumbar support 1 which is bonded to the normally
curved force-receiving sheet 42 is at rest, and hide compressive
force is applied thereagainst by the user's back. The tension
adjustment knob 16 which lies below the seat plate 14 includes a
spring (not shown: which automatically biases the chair back 2 to
the upstanding position shown in FIG. 1 at which the tension on the
tension strap 58 is maximized.
[0028] In its relaxed configuration shown in FIG. 1, the resilient
cushion back support 40 has a generally thick, convex shape which
protrudes forwardly from within the chair back 20 (best shown in
FIG. 6) towards the user so as to fit comfortably within and
provide support for the user's lower back. As previously explained,
the normally curved (i.e., arced) nature of the flexible sheet 42
pushes the convex back support 40 into engagement with the user's
back. To this end, the sheet bending rod 66 (of FIGS. 4 and 5)
applies pressure to the bottom of the flexible force-receiving
sheet 42 and urges the sheet 42 towards its normally curved
configuration. By virtue of the foregoing, the convex cushion back
support 40 maintains a proper back posture as the user is working
adjacent the work surface. At the same time, the back
pressure-responsive rod 50 of the lumbar support 1 lies at the
bottom of the pair of guide tracks 56. and the tension strap 58
stands vertically and at full tension inside the chair back 20.
[0029] FIG. 2 shows the chair 3 rocked back, the user reclining and
shining his weight against the chair back 20 and the chair back 20
tilting away from the work surface. In this case, a compressive
force is generated by the user's back against the chair back 20 to
cause the resilient cushion back support 40 to be compressed, in
its compressed configuration as shown in FIG. 2, the shape of the
formerly at-rest cushion back support 40 changes from being
initially convex to a shape which is now substantially flattened so
as to provide continuous support for the user's lower back. The
normally curved (i.e., arced) flexible force-receiving sheet 42
attached to the rear of the cushion back support 40 follows the
shape of the users back so as to be pushed backwards and
straightened. That is to say, the compressive force generated by
the user's back against back support 40 overcomes the initially
curved configuration of the flexible sheet 42 such that the sheet
is stressed and energy is stored.
[0030] When the user shifts his weight and generates a compressive
force against the chair back 20, the vertical tension strap 58 to
which the back pressure-responsive rod 50 is attached is
correspondingly pushed backwards and rotated (i.e., in a
counterclockwise direction) relative to the stationary tilt plate
60 at the spring-loaded hinge 62. At the same time that the cushion
back support 40 is compressed and flattened and the tension strap
58 rotates at lunge 62, the horizontally-extending back
pressure-responsive rod 50 which is attached to the force-receiving
sheet 42 of the back support 40 by brackets 52 is pulled by the
rotating tension snap 58 so as to ride upwardly along the pair of
guide tracks 56 and move vertically through the chair back 20.
Moreover, as the flexible force-receiving sheet 42 is pushed back
and straightened, the sheet bending rod 66 is caused to rotate
within the axially-aligned lunges 67-1 67-2, 67-3 and 67-4. Hence,
the compressive force generated by the users back against the chair
back 20 is transferred to and dissipated by the upwardly moving rod
50 and the rotating sheet head tag rod 66.
[0031] When the user shifts his weight forwardly in the chair 3 and
the compressive force being applied to the chair back 20
terminates, the back pressure-responsive rod 50 will automatically
move in an opposite direction with respect to the chair back 20 and
ride downwardly along the grade tracks 56 to its original position
shown in FIG. 1. What is more, the stressed and straightened
force-receiving sheet 42 will relax and release its stored energy
so as to recover to its initial normally curved (i.e., arced)
configuration. In this same regard, the sheet bending rod 66 is
rotated in hinges 67-1, 6722, 67-3 and 67-4 to once again push the
flexible sheet 42 against cushion back support 40. Accordingly, the
substantially flattened resilient cushion back support 40
simultaneously expands and is returned by the flexible
force-receiving sheet 42 to its initial at-rest convex shape of
FIG. 1. What is more, the tension strap 58 rotates forwardly (i.e.,
in a clockwise direction) at hinge 62 to return it its initial
vertical position inside the chair back 20, whereby to pull the
pressure-responsive rod 50 downwardly along the guide tracks
56.
[0032] It has been explained when describing the preferred
embodiment for the dynamic lumbar support 1 that the flexible
force-receiving sheet 42 that is attached to the back support 40 is
normally curved and then straightened or flattened in response to
the user leaning against the chair back 2. However, the flexible
force-receiving sheet 42 may also be normally flat and initially
forced into an arced configuration by the position of the back
pressure-responsive rod 50 and the sheet bending rod 66 when the
chair back 2 is in the upright position of FIG. 1. When the user
leans back and the chair is tilted, the force-receiving sheet 42 is
then urged to its original flattened shape to relieve the initial
stress and release the energy stored by being bent.
* * * * *